The present disclosure relates generally to toner image reproduction machines, and more particularly, concerns such a machine including a ball valve device having a pressure release assembly.
In a typical toner image reproduction machine, for example an electrostatographic printing process machine contained within a single enclosing frame, an imaging region of a toner image bearing member such as a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is irradiated or exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document.
After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed at a development station by bringing a developer material in a developer housing into contact therewith. Generally, the developer material comprises magnetic carrier particles and toner particles that adhere triboelectrically to carrier particles. During development, the toner particles are attracted from the carrier particles to the latent image thereby forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are then heated by a fusing apparatus within the single enclosed frame to permanently affix the powder image to the copy sheet.
Toner particles in the developer material in the developer housing accordingly become more and more depleted during image development as described above, ordinarily resulting in diminishing image quality. To maintain image quality, fresh toner particles therefore must be regularly added to the development. It has also been found that image quality can further be improved by regularly also adding fresh carrier particles to the developer housing, for example, using a carrier replenishment system.
Such a carrier replenishment system may include use of pressurized storage hopper that requires refilling under pressure. In general as with other applications, refilling a pressurized hopper under pressure from a fresh material container such as a bottle would be a problem because during the refilling the container or bottle will itself ordinarily become pressurized and hence under the same pressure as the hopper. As such, removing the container or bottle when refilling is complete (even after sealing the hopper) would be a problem because the pressurized air within the container (after it is empty) will tend to blow remnant material from the container all around causing a mess and a safety hazard.
There is therefore a need for a valve device that can enable refilling of a pressurized hopper from a container “while running” without compromising the pressure within the hopper and without the ordinary messy and hazardous results from residual pressure within the container.